U.S. Pat. No. 4,800,313 to Warner, et al., whose contents are incorporated herein in their entirety by this reference, details examples of brush holders for use with carbon brushes. These holders utilize ribbon springs so as to provide essentially constant biasing force to the brushes. They are, in at least this aspect, conventional, as the use of constant biasing force is known generally to reduce maintenance, prevent performance problems, and increase the useful lives of the brushes.
Commutators or slip rings and associated carbon brushes and holders are used in numerous industrial contexts. Some such uses are for power generation. Collector brush riggings provided by original equipment manufacturers (OEMs) typically accept certain brush-holder designs, many of which are not designed to allow easy brush replacement while equipment is operating. Consequently, when a brush is worn such that its useful life has expired, the corresponding power-generation equipment must cease operation before the brush may be replaced safely. In practice, however, some equipment operators replace brushes without ceasing operation of the equipment, conduct carrying a high risk of injury.
Efforts have been made to supply improved brush holders which permit on-line replacement of brushes. Currently-available holders of this type are expensive and cumbersome, however, or may require extensive or expensive modifications to the associated equipment (such as the brush holder support system). In many cases, the replacement brush holders accept brushes significantly shorter than the original-equipment brushes and are not interchangeable with existing OEM devices.